Production of interferon α and β, pro-inflammatory cytokines and the expression of suppressor of cytokine signaling (SOCS) in obese subjects infected with influenza A/H1N1

Summary Background & aims Obesity was recognized as an independent risk factor for morbidity and mortality during last influenza A/H1N1 pandemic. Mechanisms involved in the high mortality risk from obesity during influenza A virus include reduced type I interferon production and delayed pro-inflammatory response, which lead to a higher rate of morbidity and mortality in murine models. In this study, we evaluated the production of type I interferons, pro-inflammatory and anti-inflammatory cytokines in peripheral blood mononuclear cells (PBMCs) from obese and lean subjects with and without confirmed infection of influenza A/H1N1. The expression levels of the suppressor of cytokine signaling-1 (SOCS1), SOCS3 and nuclear factor-kB were also evaluated. Methods Cytokines were measured by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) and/or by ELISA in PBMCs stimulated with toll like receptor-3 (TLR-3) and TLR-7 ligands. The mRNA expression of SOCS1 and SOCS3 were evaluated by qRT-PCR. Results The obese volunteers infected with influenza A/H1N1 showed a diminished ability to produce type I interferon in response to TLR-3 ligand. Interestingly, the pro-inflammatory response was also affected in TLR-3 stimulated PBMCs. Obese influenza-free volunteers showed an increased basal expression of SOCS3, but not SOCS1. During influenza infection, SOCS1 and SOCS3 expression was higher in the lean infected volunteers in contrast to those who were obese infected. Conclusions These data suggest that obesity is related to TLR-3 impairment and explain, at least in part, the inadequate immune response of obese individuals during infection with influenza A/H1N1 virus.